Best solar panels for the buck

[Maine Sail]

If you buy 12 volt nominal panels your batteries will not charge!!!!!!!
You need AT THE VERY LEAST 14.4 volts output with hot panels. Either 36 cells or 18 volts is considered the MINIMUM needed to effectively charge a "12 volt wet cell" battery.
Remember a "12 volt battery" does not operate at 12 volts and is almost dead when it gets to 12 volts. 13.6 is the standard resting voltage for a fully charged battery so plugging in a 12 volt nominal panel will not accomplish much of anything except to empty your wallet.

Bill where do you come up with this stuff..? 13.6 fully charged? I don't know of any 12V battery that has a "resting voltage" of 13.6 for full charge? Perhaps you could point us to one? Float charging is 13.2 -13.8 volts for most brands, take away the float, and most all 12V batteries will "rest" at under 13 volts. Some will hang out at a voltage above 13 for a while when colder but all will eventually rest quite a big lower than 13.6V. Trojan wet cell batteries for example have a 100% charge when resting at 12.73V open circuit voltage. Some AGM's are slightly higher with Lifeline & Deka coming in at about 12.8V for 100% SOC at 77F..

A 12V "nominal" panel is not 12V they are usually 16+ volts. Even a 25V panel can be considered a 12V panel because 25 volts is not enough to charge a 24V battery.. If you had a 12V panel, and that was the actual Vmp, then it would not charge a 12V battery and would ideally be classified as a 6V or 8V nominal panel...

Nominal: a : existing or being something in name or form only <nominal head of his party> b : of, being, or relating to a designated or theoretical size that may vary from the actual : approximate <the pipe's nominal size>

Nominal is a term very often used to describe the panels "classification", such as 12 or 24V not the actual Vmp of a panel...

Here's a link that describes "nominal" and other nomenclatures: http://www.altestore.com/howto/Sola...-Components/Solar-Panels-PV-and-Voltages/a98/

 

[prroots]

I'd be interested in recommendations for MPPT charge controllers. At the moment, I'm comparing Blue Sky SB3024iL with Morningstar TS-MPPT-45. The Morningstar has a standard RS232 interface to control and monitor operation via a PC. The Morningstar claims a 99% efficiency vs 97% claimed for the Blue Sky. I'm sure there are many more significant differences, but overall the Morningstar seems to have a greater range of Voltages and current with more flexibility. For example, the Morningstar works with nominal PV voltages of 12, 24, and 48 with maximum current output of 45 Amps. The Blue Sky works with nominal PV voltages of 12 and 24 with max currents of 32 and 12 Amps respectively.
Pete

 

[Maine Sail]

I'd be interested in recommendations for MPPT charge controllers. At the moment, I'm comparing Blue Sky SB3024iL with Morningstar TS-MPPT-45. The Morningstar has a standard RS232 interface to control and monitor operation via a PC. The Morningstar claims a 99% efficiency vs 97% claimed for the Blue Sky. I'm sure there are many more significant differences, but overall the Morningstar seems to have a greater range of Voltages and current with more flexibility. For example, the Morningstar works with nominal PV voltages of 12, 24, and 48 with maximum current output of 45 Amps. The Blue Sky works with nominal PV voltages of 12 and 24 with max currents of 32 and 12 Amps respectively.
Pete

Personally I tend to prefer Morningstar products but they also tend to be a little more expensive and have some holes in their MPPT line up by jumping from 15A to 45A.. Many boat systems are above 15A but well below 45A as a result there is a $200.00 hole in their product line... IMO Morningstar controllers are built to handle the marine environment slightly better, but there is still nothing wrong with Blue Sky and they hold up well.. I install both.

With only 20+/- amps why not consider a less expensive Blue Sky? If you're goiing to spend $450.00 on a controller, and then buy panels of unknown proven history in the marine environment, it just seems odd...? Please DO NOT get all wound up over "claimed efficiencies" they can and will make this data say what ever they want. I've NEVER seen an MPPT add more than 13-14% but they claim up to 30%. They often add 2-10% and the occasional 13%+ is quite rare unless you have some 12V panels pushing 25V as opposed to 18V.

The computer connection, in my view, is a wallet grab. Just another "feature" most never use that the manufacturer spends a couple dollars on and chargers a $80.00 premium for. A remote display is useful but computer connection, not so much.. A standard battery monitor for $180.00 will tell you all you need to know about your house bank without drawing 2-7A to do so as a computer will...

If I was spending $450.00 on a TS-45 MPPT it would be fed with Kyocera or another known premium "A" grade panel that I know to hold up for the long haul in a marine application.. Just my take... The 2512i or 2512iX would suit you fine based on what you are planning and the 2512i can be had f0r under $170.00, if you shop around.. .

 

[prroots]

Personally I tend to prefer Morningstar products but they also tend to be a little more expensive and have some holes in their MPPT line up by jumping from 15A to 45A.. Many boat systems are above 15A but well below 45A as a result there is a $200.00 hole in their product line... IMO Morningstar controllers are built to handle the marine environment slightly better, but there is still nothing wrong with Blue Sky and they hold up well.. I install both.

With only 20+/- amps why not consider a less expensive Blue Sky? If you're goiing to spend $450.00 on a controller, and then buy panels of unknown proven history in the marine environment, it just seems odd...? Please DO NOT get all wound up over "claimed efficiencies" they can and will make this data say what ever they want. I've NEVER seen an MPPT add more than 13-14% but they claim up to 30%. They often add 2-10% and the occasional 13%+ is quite rare unless you have some 12V panels pushing 25V as opposed to 18V.

The computer connection, in my view, is a wallet grab. Just another "feature" most never use that the manufacturer spends a couple dollars on and chargers a $80.00 premium for. A remote display is useful but computer connection, not so much.. A standard battery monitor for $180.00 will tell you all you need to know about your house bank without drawing 2-7A to do so as a computer will...

If I was spending $450.00 on a TS-45 MPPT it would be fed with Kyocera or another known premium "A" grade panel that I know to hold up for the long haul in a marine application.. Just my take... The 2512i or 2512iX would suit you fine based on what you are planning and the 2512i can be had f0r under $170.00, if you shop around.. .

Thanks. We just order two 24 Volt / ~200 Watt panels from SolarBlvd to supply our four golf cart batteries. They are "B grade" panels which should have met a spec of 210 Watts, but didn't. The cost was $200 each ie, $1.00/watt. There was an interesting story to go with the panels. SolarBlvd ordered 10 "B grade" panels to resell. Eight of them were 12 Volts / 185 watt panels as ordered; the other two were 24 volt panels shipped (apparently) by mistake. I'm guessing they were a nuisance to sell and hence, the steep discount. Anyway, we hope SolarBlvd is a reputable company as has been reported. We also purchased the Morningstar TS-MPPT-45 controller for $370 with price matching plus a battery temperature sensor. We splurged on the controller, but really like it's flexibility which will come in handy if we ever have to change out the panels for something else down the road; they handle nominal 12-48 volt panels. BTW, the Morningstar manual for this controller gives efficiency curves as a function of battery voltage and Vmp. Apparently the controller has 3 parallel converters of 15 Amps each. As amperage increases the next circuit cuts in. They claim this gives higher efficiency than their competitors!?
Pete

 

[Sumner]

I assume that you know that if down the road you want to mix 12 volt panels with the 24 you are going to take an efficiency hit even if the controller can work doing that? When I talk to them (Solar Blvd) I try and talk to the head guy, can't remember his name, not a sales person if I have a technical question. Also I've talked to the Blue Sky techs and they have explained some things better than the guys at Solar Blvd, but Solar Blvd has always been prompt and honest with me. No complaints there.

The MPPT controllers are more efficient than the PWM when the batteries are at lowest charge. As the battery voltage goes up they get closer to each other. The 30% they like to quote is when the batteries are low and there is a bigger difference between them and the panels.

Good luck with the panels,

Sum

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[prroots]

I assume that you know that if down the road you want to mix 12 volt panels with the 24 you are going to take an efficiency hit even if the controller can work doing that? When I talk to them (Solar Blvd) I try and talk to the head guy, can't remember his name, not a sales person if I have a technical question. Also I've talked to the Blue Sky techs and they have explained some things better than the guys at Solar Blvd, but Solar Blvd has always been prompt and honest with me. No complaints there.

The MPPT controllers are more efficient than the PWM when the batteries are at lowest charge. As the battery voltage goes up they get closer to each other. The 30% they like to quote is when the batteries are low and there is a bigger difference between them and the panels.

Good luck with the panels,

Sum

Thanks. I've spoken to two different people at SolarBlvd. The one who is more knowledgeable is Prashant Shewa or Shawn for short. The other person refers me to Shawn when we get into the details. If a panel needs to be replaced down the road due to either warranty issues or damage, it could be a problem since they're "one off". Shawn said in that case let them know and they'll work with me to find a suitable replacement. At that point, a lot will depend on the good will of Solar Blvd. Basically, I shopped for best $/watt on the panels, but stuck with a top of the line controller. We'll see how that works out.

Can anyone recommend a type of cable and source? I will probably go with 6 AWG / 2 conductor. It should be UV rated. I will cut off the supplied connectors and wire to a watertight junction box.
Pete

 

[Sumner]

....Shawn.....

Can anyone recommend a type of cable and source? I will probably go with 6 AWG / 2 conductor. It should be UV rated. I will cut off the supplied connectors and wire to a watertight junction box.
Pete

Yep that is who I try and talk to.

I've been getting wiring from...

http://shop.genuinedealz.com/

...Since I needed #4 I had to get the single conductor. I see in #6 that two singles looks cheaper than one 2 conductor. Also I don't think it has a UV rating, but didn't look long. I'll probably put mine in that plastic loom stuff, but remember our boat won't be in the water all of the time. The wiring to the panels on the Mac is the 2 conductor and after a year looks fine. I'll use the same from the panels to the junction box. It is under the panels there.

MS what do you do?

Sum

[FONT=Arial, sans-serif]Our Endeavour 37[/FONT]

[FONT=Arial, sans-serif]Our Trips to Utah, Idaho, Canada, Florida[/FONT]

[FONT=Arial, sans-serif]Our MacGregor S Pages[/FONT]

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[prroots]

Having bought my panels and controller, I'm now turning my attention to the design of a mount to be placed on top of my existing dinghy davits. My thoughts so far are:
- construct an aluminum frame from 1-1/2 X 2 inch angle such that two panels drop into it oriented end-to-end and placed athwartship on top of dinghy davits. Overall size will be 116" X 39"
- build a support structure from 1" OD stainless tubing that creates a horizontal tube 67" long in the athwart ship direction and approximately 20" above the dinghy davits. The shape will be that of an inverted 'U' with right angle corners to maximize width. This height will minimize shading from bimini and provide clearance to raise and lower outboard from its mount.
- attach the frame to the tube using 2 or 3 of those plastic rail clamps available from West Marine (can't find them anywhere else). This allows panels to be tilted in the fore and aft direction and isolates aluminum frame from stainless tube.
- weld a perforated aluminum semi-circle to underside of frame just outside the 1" stainless support structure. A tab on stainless tube will allow the panel to be locked at the desired angle. Use a stainless aircraft pin to lock.

My concerns at this point is:
1. the amount of overhand of the panels which amounts to 24-1/2 inches on either end. The frame will have to be stiff enough to support this. If the boat is pitching in heavy seas this could cause considerable flexing.
2. I'm hoping that the simple tilt lock mechanism will be stiff enough.

I've attached a crude hand-drawn sketch which hopefully will be worth a 1000 words! Comments and suggestions appreciated.
Pete

 

[KD3PC]

three things i see....

is there enough "meat" to hang another stainless ring off the stern of the B-411...with davits and other stuff...my 36CC was fairly thin back there...?

the overhang would bother me, as panels really don't like to flex..crack perhaps...but they will not flex. Any flex will be translated in to deterioration and weather getting in to places not intended for it. So your frame must be quite sturdy.

I would do away with the tilt lock and calculate where you want the panels to sit and firmly attach that second point to the stainless...down side is that all of your attachments are in the center of the panel and both attach to the 1" stainless, if I see it correctly.

 

[prroots]

three things i see....

is there enough "meat" to hang another stainless ring off the stern of the B-411...with davits and other stuff...my 36CC was fairly thin back there...?

the overhang would bother me, as panels really don't like to flex..crack perhaps...but they will not flex. Any flex will be translated in to deterioration and weather getting in to places not intended for it. So your frame must be quite sturdy.

I would do away with the tilt lock and calculate where you want the panels to sit and firmly attach that second point to the stainless...down side is that all of your attachments are in the center of the panel and both attach to the 1" stainless, if I see it correctly.

Thanks. I don't understand this

is there enough "meat" to hang another stainless ring off the stern of the B-411

Yes, the overhang is an issue, but at some level the frame can be made stiff enough to adequately support the panels. The challenge is knowing how strong the frame need be.

Yes, the attachment is along the center-line of the panels. We will construct the mount without the tilt lock and then evaluate before proceeding. I'm already thinking that I will need a diagonal brace between the vertical section of 1" stainless tube and another part of the dinghy davit. This would greatly reduce the stress on the weld joint where the vertical tube joins the davits.
Pete

 

[KD3PC]

Thanks. I don't understand this

Pete

I am just asking if there is enough fiberglass and access to epoxy in some backing board, metal plates or bracing structure to handle the weight, and the windage weight added by the panels hanging off the back. I assume you already davits installed, and the usual grill, OB, antennas, etc.

On my 36CC, access to that part of the boat was all but impossible and the glass - being above the water line and in all kinds of compound curves was actually quite thin - to use for structural add ons.

 

[Sumner]

It is hard for me to tell from the drawing so some of what follows might not pertain.

Unless the uprights were pretty large tubing and very secure at their bases you need some diagonals fore/aft and side to side.

I wouldn't use the plastic at all where you have it planned. See if this site...

http://www.marinepartdepot.com/newststdehi.html

...might have something that would do what you are trying to do out of stainless.

I broke the one panel on the piling at Marco Island, but it did still actually work and none of the other panels broke and the whole support structure just had some bends that I was able to straighten 90% on the water and finished at home. I have lots of diagonals though. The whole thing has seen thousands of highway miles with no problems. 65 on the highway into 45 mph winds is like 100 mph winds, so it has to be strong, but still on the water sooner or latter you could get 60-70 mph wind.

My latest configuration has one panel...

...the 40 watt, that tilts up where it is shown or flat or down the same amount as the up. I don't think you need so much adjustment. Even if you can adjust it some you still might have the sun angle from abeam. One reason for 480 watts on the Endeavour is so that hopefully we are 'over paneled' as I didn't want to make the panels movable or have to deal with trying to track the sun. Making large panels movable and still strong is going to take some work.

In a week or so I'll be making the panel mounts above the bimini for the Endeavor and will have some pictures. It will be somewhat different than what I did on the Mac...

http://purplesagetradingpost.com/sumner/macgregor2/outside-33.html

...as there will be a lot more panels up there. I hope it is over-built some. Also I'll try and get some pictures up on how I'm hinging the 40 watt panel above. I have them, just haven't posted them.

I'm making the mount and all mount hardware out of aluminum, but I think if we were going to be full time cruisers with the boat in saltwater I'd spend more and go all SS,

Sum

[FONT=Arial, sans-serif]Our Endeavour 37[/FONT]

[FONT=Arial, sans-serif]Our Trips to Utah, Idaho, Canada, Florida[/FONT]

[FONT=Arial, sans-serif]Our MacGregor S Pages[/FONT]

[FONT=Arial, sans-serif]Mac-Venture Links[/FONT]

 

[prroots]

I am just asking if there is enough fiberglass and access to epoxy in some backing board, metal plates or bracing structure to handle the weight, and the windage weight added by the panels hanging off the back. I assume you already davits installed, and the usual grill, OB, antennas, etc.

Ok, now I understand. The davits are attached to both the transom and stern pulpit as shown in the attachment. Good point; I have not checked whether there are any backing plates. Of course, we carry the dinghy on the foredeck when making a passage. Basically the dinghy davits are used to secure the dinghy against theft when at anchor. Therefore, the davits will not usually need to bear the weight of the dinghy; just the panels
Pete

 

[prroots]

Unless the uprights were pretty large tubing and very secure at their bases you need some diagonals fore/aft and side to side.

I wouldn't use the plastic at all where you have it planned. See if this site...

http://www.marinepartdepot.com/newststdehi.html

.[FONT=Arial, sans-serif]http://purplesagetradingpost.com/sumner/macgregor/macgregor-links-1.html[/FONT]

Thanks. I think you're right about needing some diagonal braces. I've factored that into the design. That's a nice link with lots of interesting hardware. I do think the nylon clamps are nice though and I can always double them up if need be. They isolate the SS from aluminum and make it easy to disassemble.
Pete

 

[Sumner]

I sent you an e-mail with a sketch. Let me know if you didn't get it,

Sum

 

[prroots]

I sent you an e-mail with a sketch. Let me know if you didn't get it,

Sum

Got it; thanks
Pete

 

[prroots]

The mount will include an aluminum frame made from angle. Can anyone recommend the type of aluminum for best strength and corrosion resistance? I'm wondering if it should be anodized. I want to be sure to include the type in the spec for the fabricator.
Pete

 

[prroots]

We're seriously considering rearranging the orientation of the two 39" X 58" panels such that they are side-by-side with long dimension of panels oriented fore and aft. This would make the combination 78" in the athwartship direction and 58" in the fore and aft direction. The positives are 1) the panels are much less vulnerable when docking and 2) they are better supported in the athwartship direction by the inverted-U mount. The negative are 1) they are more prone to shading from bimini when tilted forward, 2) the tilt lock has to work against more weight (ie, overhang), and 3) they extend the length of the boat. The shading issue will probably force us to raise the panels a bit more. With this orientation, they only overhang the ends of the inverted-U mount by 5-1/2" vs 24-1/2" which seems more reasonable. Comments welcome.
Pete

 

[prroots]

We checked with the local metals outfit for the best type of aluminum to be used in the construction of the frame for solar panels. They recommended aluminum alloy 6463 bright dipped anodized. They said this is what the tuna towers are mostly built from. Has anyone experience with this or other aluminum alloys? With respect to angle it only comes in 2 X 2 X 1/4.
Pete

 

[prroots]

My Morningstar Tristar MPPT 45 controller arrived yesterday. I'm really impressed by its construction and features. It has a maximum PV (input) voltage rating of 150 Volts and maximum PV (input) current of 45 Amps so it's a bit overkill, but should provide great performance. It can handle system (battery) Voltages from 12 to 48. I watched a training video on it at:
http://www.morningstarcorp.com/en/su...cfm?ItemId=444
and it uses a very fast complete sweep of PV IV curve to set maximum power point; pretty sophisticated overall. Competitors do dynamic sweeping which just looks at a limited portion of the IV curve near the current setting. This can miss better power points when the IV curve has bumps in it. This is, of course, a bit of marketing; not sure to what degree it's significant.

My (two 200 Watt) panels have been delayed and won't arrive until Monday. This will give me a bit more time to fine tune the solar mounting. The support frame and tilt lock will be constructed from bright dipped anodized aluminum 6463 and the support structure from type 316 stainless steel.
Pete